I want to add that the so-called hatchback effect has more to do with the space in the car than bass bouncing off anything like trunk walls, windows etc. A typical hatch has somewhere on the order of 100-120 cu ft while mid sized cars have closer to 150 cu ft. What happens is the transfer function occurs at a higher freq.
As the others have said, bandpass boxes can be made to sound good, but it isn't easy.
